You'll have to forgive the technical inaccuracies with this picture:

Castle's would never:
   Illuminate their guard towers so that enemies could see them better.
   Have a guard on duty with a halberd axe instead of a bow.
   Have a band around the walls to help enemies scale them.
   Have such short walls.
   Have such a small moat.

But ignoring these minor theoretical points, I feel the picture is turning out rather well.

Also, it's amazing how particles can affect the render time. This picture renders in about 4 mins. on my PII/233 w/ 64MB RAM. If I add a small tree using particles in the background (the current tree is not using particles), it takes 3 hours.